Radar is widely used for determining positions of objects relative to an observer. These objects may be immobile or moving. Radar works by emitting microwave radiation in those directions where said objects are positioned, and detecting the reflected radiation from those objects. In order words, a radar first sends microwave radiation, and then receives the reflections of said microwave radiation, when these are reflected by various objects. By analyzing these reflections, it is possible to determine the positions and radial velocity of the objects.
In order to cover a wide azimuth sector, preferably 360°, rotating turntables carrying a transmitting antenna are used. These turntables are, however, quite heavy, expensive and require maintenance. Furthermore, these antennas will only cover a certain angular direction for a fraction of the available time.
Another approach is to use array antennas with a plurality of antenna elements. By feeding the antenna elements with certain phases and amplitudes, the array antenna's radiation lobe may be electrically controlled. These array antennas are usually called phased array antennas. Phased array antennas are, however, expensive and require a large number of receivers and, in some configurations, a large number of signal generators.
Therefore, there exists a need for an inexpensive radar system without moving parts which covers 360° in azimuth and comprises inexpensive and easily handled parts.